The present invention claims priority to priority document No. P2000-302485 filed in Japan on Oct. 2, 2000, and incorporated by reference herein.
1. Field of the Invention
This invention relates to a parts replacing method and a parts replacing apparatus for replacing electronic parts mounted on a substrate, and such parts are mainly electronic parts mounted on a printed circuit board to be installed in an electronic appliance.
2. Related Art
Generally, various kinds of electronic parts such as BGA (Ball Grid Array) elements are arranged on a mounting (circuit) board. In a manufacturing process for mounting various parts on the circuit board, sometimes, mounting defects are detected at some of mounted electronic parts through an inspection process usually done after mounting these electronic parts on the circuit board. In this case, it is necessary for such defectively mounted piece of electronic parts to be removed among plural electronic parts mounted on the circuit board, and to remount a new piece of electronic parts at the removed position of the circuit board.
FIG. 13 shows one example of a conventional electronic parts replacing method for replacing defectively mounted a piece of parts to new piece. Conventionally, in an electronic parts mounting apparatus (such as called a chip mounter), a circuit board 120 is placed on a table 103 and a defectively mounted piece of electronic parts (here-in after called as a piece of electronic parts to be replaced) 99 is removed from the circuit board 120 by a work head 101, and after putting it away, a new piece of electronic parts (here-in after called as a piece of replacing electronic parts) 100 is picked up by the work head 101 and remounted on a position where the piece of electronic parts 99 to be replaced is mounted on the circuit board 120.
When such new piece of replacing electronic parts 100 is mounted after the piece of electronic parts 99 to be replaced is removed from the circuit board 120, it is necessary to mount the new piece 100 precisely on the right position where the piece of electronic parts 99 to be replaced is previously mounted. If the piece of replacing electronic parts 100 is mounted to a position where is slightly differed from the position of the removed piece of electronic parts 99 to be replaced, this causes again defective mount of the electronic parts.
In order to precisely position the piece of replacing electronic parts 100 to the position where the piece of electronic parts 99 to be replaced are mounted, three kinds of methods as shown in FIG. 14 to FIG. 16 have been practiced conventionally.
In any of these conventional methods, the positioning of the replacing electronic parts 100 is done with reference to the pattern P that is provided on a position where the piece of electronic parts 99 to be replaced is previously mounted.
In the conventional method as shown in FIG. 14, the piece of replacing electronic parts 100 held by a work head 101 is positioned almost above the pattern P on the circuit board 120 and between the piece of replacing electronic parts 100 and the circuit board 120, an optical apparatus 104 is provided for superposing an image of the piece of replacing electronic parts 100 on an image of the pattern P, and the image obtained through the optical apparatus 104 is to be inspected using a CCD (Charge Coupling Device) camera 105.
An operator moves the work head 101 or the table 103 for the fine adjustment as to perfectly superpose the image of the piece of replacing electronic parts 100 and the image of the pattern P, while watching the monitor 106 connected to the CCD camera 105, and after that the operator moves the work head 101 downwardly for mounting the piece of replacing electronic parts 100 on the circuit board 120.
Further in the conventional method shown in FIG. 15, the image of the replacing electronic parts 100 and the image of the pattern P are obtained through two CCD cameras 107 and 108, these images are superposed by an image superposing apparatus 109 and then displayed on the monitor 110. The operator, while watching the monitor 110, moves the work head 101 (or table 103) for carrying out the fine adjustment so as to superpose the image of the piece of replacing electronic parts 100 and the image of the pattern P, and after that the operator moves the work head 101 down to mount the piece of replacing electronic parts 100 on the circuit board 120.
In addition in the conventional method shown in FIG. 16, a mask 111 having the same pattern as the pattern P on the circuit board 120 is provided above the table 103 where the circuit board 120 is placed. The operator, while watching the pattern P on the circuit board 120 and the mask 111, moves the table 103 for fine adjustment as to position the work head 101 on a predetermined position on the mask 111. After that, the mask 111 is removed between the piece of replacing electronic parts 100 and the circuit board 120 the work head 101 is moved downwardly, and the piece of replacing electronic parts 100 is mounted on the circuit board 120.
In accordance with the above-mentioned conventional methods as shown in FIG. 14 to FIG. 16, it is necessary to carry out the fine adjustment of the work head 101, so that the operator is required enough experience and further it takes much time to replace the electronic parts. Further in the above mentioned conventional methods shown in FIG. 14 and FIG. 15, various equipments such as CCD cameras, optical devices, an image superposing apparatus or a monitor are necessary, so that there exists another problem such as increase of manufacturing costs. In addition, according to the conventional method shown in FIG. 16, fine adjustments of the positioning for the work head are done with human eyes, so that when the electronic parts are aligned in very fine pitches, such adjustment work takes long times, or sometimes it becomes difficult to perform by human eyes.
A parts replacing method of the present invention preferably comprises the steps of: holding step for holding a piece of parts to be replaced mounted at a predetermined position of a substrate by a holding section of a parts holding means; removing step for removing the piece of parts to be replaced from the substrate by moving the parts holding means away from the substrate, while guiding the parts holding means by the guide means; replacing step for removing the piece of parts to be replaced from the holding section of the parts holding means and for attaching a piece of replacing parts to the holding section; and mounting step for mounting the piece of replacing parts held at the holding section by moving the parts holding means close to the substrate, while guiding the parts holding means by the guide means.
Further a parts replacing apparatus of the another aspect of the present invention comprises: a parts holding means having a holding section for holding a piece of parts to be replaced for removing the piece of parts to be replaced held at the holding section and for attaching to the holding section a new piece of replacing parts; and a guide means for guiding the parts holding means in the direction to move away from or close to a substrate.
According to the electronic parts replacing method or the electronic parts replacing apparatus, the piece of electronic parts to be replaced is removed from the substrate, while being guided by the guide means, after holding the piece of electronic parts to be replaced mounted on the substrate at the holding section. After that, the piece of electronic parts to be replaced is removed from the holding section of the electronic parts holding means, and then new piece of replacing electronic parts is attached to the holding section. Then the electronic parts holding means is moved toward the substrate, while being guided by the guide means, and after that the piece of replacing electronic parts held on the holding section is mounted on the substrate. The relative positional relation between the electronic parts holding means and the substrate is determined by the guide means, so that the piece of replacing electronic parts can be precisely mounted on the position of the piece of electronic parts to be replaced.